1. Field of the Invention
The present invention relates to a method of manufacturing a vacuum micro-structure to be used for elements of microelectromechanical system (MEMS) or the like that operate in vacuum, and more particularly, to a method of fabricating a MEMS structure by connecting the vacuum micro-structure with external elements.
2. Description of Related Art
An example of the related art is a method of encapsulating a microelectronic device in a vacuum chamber through a surface process, which is proposed by Boysel et al. (U.S. Pat. No. 5,354,714, Oct. 11, 1994, "Method of forming a vacuum micro-chamber for encapsulating a microelectronic device"). This method includes the steps of preparing a device on a substrate, applying an organic agent such as photoresist on the surface of the device to define a pattern, depositing a metal film, forming an open window in the metal film coated on the photoresist in order to remove the photoresist confined inside the metal film, and decomposing the photoresist to be removed with a solvent or the like. According to the method, the open window is hermetically sealed by a metal film redeposition step performed in a vacuum, thereby manufacturing a vacuum micro-element. This method, however, has a problem in that it is inapplicable to a large-sized vacuum structure because the thickness of the thin film used as a sealing material is limited to several micrometers and the vacuum pressure may transform the vacuum structure.
Another method involves use of a small-sized vacuum can but is disadvantageous in that mass productivity is poor because packaging is performed in the unit of element.
Generally, an angular velocity sensor with a vacuum microstructure that is manufactured by processing a silicon wafer in the semiconductor process includes a comb-like drive and detection electrode and a spring beam which are spatially floating over the substrate. When driving the angular velocity sensor at high frequency, however, the internal space of the structure must be kept in vacuum.